The present invention relates in general to the field of speech pathology, and is particularly directed to a process for determining whether a patient is at risk for oral or pharyngeal dysphagia, by means of a cough-based screening process for clinically evaluating the patient""s swallow.
In order to clinically detect those patients who are at risk for aspiration, speech pathologists currently employ a standard procedure for evaluating a patient""s swallow. A normal human swallow can be separated into four phases: 1)xe2x80x94oral preparation, 2)xe2x80x94the oral phase, 3)xe2x80x94the pharyngeal phase, and 4)xe2x80x94the esophageal phase. Patients who have suffered a stroke, traumatic brain injury or neuromuscular disorder (such as MS or ALS) have an increased risk of aspiration, and may have difficulty with either the oral phase, the pharyngeal phase or both, secondary to neurologic deficits. Poor tongue movement in chewing or in the swallow can cause food to fall into the pharynx and into the open airway before the completion of the oral phase. A delay in triggering the pharyngeal swallowing reflex can result in food falling into the airway during the delay when the airway is open. Reduced peristalsis in the pharynx, whether unilateral or bilateral, will cause residue in the pharynx after the swallow that can fall or be inhaled into the airway. Laryngeal or cricopharyngeal dysfunction can lead to aspiration because of decreased airway protection during the swallow.
An abnormal human swallow is termed dysphagia. The oropharyngeal physiology involved in a normal swallow is very complicated, and many different neurological disturbances can disrupt normal swallowing and can cause aspiration of food material, liquid or solid, into the lungs, leading to increased morbidity in hospitalized patients and possible pneumonia. See, for example, the article by Jeri Logemann, entitled: xe2x80x9cSwallowing Physiology and Pathophysiology,xe2x80x9d Otolaryngologic Clinics of North America, Vol. 21, No. 4, November, 1988, and the article by L. Kaha et. al., entitled: xe2x80x9cMedical Complications During Stroke Rehabilitation, Stroke Vol. 26, No. 6, June 1995.
Speech pathologists have tried many procedures to detect or predict aspiration in patients with neurological deficits. Although the standard bedside swallow exam to screen patients is beneficial for evaluating patients at risk for oral or pharyngeal dysphagia, studies have shown that, when compared to a modified barium swallow (MBS) videofluoroscopic examination, it is neither very specific nor sensitive in detecting aspiration. See, for example, the article by Mark Splaingard et. al. entitled: xe2x80x9cAspiration in Rehabilitation Patients: ideofluoroscopy vs. Bedside Clinical Assessment; Archives of Physical Medicine and Rehabilitation, Vol. 69, August, 1988, and the article by P. Linden, et. al., entitledxe2x80x9d xe2x80x9cThe Probability of Correctly Predicting Subglottic Penetration from Clinical Observationsxe2x80x9d, Dysphagia, 8: pp 170-179, 1993.
As discussed in the above-referenced Logemann article, and also in an article entitled: xe2x80x9cAspiration of High-Density Barium Contrast Medium Causing Acute Pulmonary Inflammationxe2x80x94Report of Two Fatal Cases in Elderly Women with Disordered Swallowing,xe2x80x9d by C, Gray et al, Clinical Radiology, Vol. 40, 397-400, 1989, videofluoroscopic evaluations are more costly than bedside evaluations and videofluoroscopy is not entirely without risk. Because of the poor predictability of the present bedside exams, the MBS is being used more and more with its increased reliability for diagnosing aspiration. Many studies using videofluoroscopy have tried to pinpoint the exact anatomical or neurological deficit causing the dysphagia, as well as what stage of the swallow is primarily affected in different disorders.
Patients that have a head injury, stroke or other neuromuscular disorder can aspirate before, during, or after the swallow, and a high percentage can be silent aspirators. Unfortunately, these patients might not display any indication of aspiration during a clinical exam but can be detected by the MBS, as discussed in the Logemann article and in an article by C. Lazurus et al, entitled: xe2x80x9cSwallowing Disorder in Closed Head Trauma Patients,xe2x80x9d Archives of Physical Medicine and Rehabilitation, Vol. 68, February, 1987, an article by J. Logemann, entitled: xe2x80x9cEffects of Aging on the Swallowing Mechanism,xe2x80x9d Otolaryngologic Clinics of North America, Vol. 23, No. 6, December 1990, and an article by M. DeVito et. al., entitled: xe2x80x9cSwallowing Disorders in Patients with Prolonged Orotracheal Intubation or Tracheostomy Tubes,xe2x80x9d Critical Care Medicine, Vol. 18, No. 12, 1990.
The bedside swallow exam performed by most speech pathologists evaluates history, respiratory status, level of responsiveness and an oral exam. The oral examination includes a detailed evaluation of the muscles of mastication, lips, tongue, palate, position patient tested in as well as the swallowing evaluation. Sensation, various movements and strength are carefully evaluated. In the pharyngeal stage, the patient is tested for a dry swallow, thin liquid, thick liquid, pureed textures and solid textures.
A typical bedside exam looks for nasal regurgitation, discomfort or obstruction in the throat or multiple swallows, as well as any visible signs that may indicate risk for aspiration, gurgling, impaired vocal quality, and coughing. The bedside exam results are then analyzed to determine whether the patient should have an MBS study to evaluate swallowing physiology and to rule out aspiration. Although the bedside exam is very thorough, and can identify patients who are at risk for or have dysphagia, it is not effective in determining which patients will aspirate.
In addition to the foregoing, speech pathologists have historically had difficulty studying the sensory afferents of the larynx involved in airway protection. As described in an article by J. Widdicombe et al, entitled: xe2x80x9cUpper Airway Reflex Control,xe2x80x9d Annual New York Academy of Science, Vol. 533, 252-261, 1988, the sensory afferents for general coughing travel the internal branch of the superior laryngeal nerve. A patient may have a voluntary cough present with the efferent motor system intact, but not have any sensation on the larynx secondary to the afferents becoming completely or partially affected, which would be indicative of risk for silent aspiration.
As described above, the MBS test is of value to patients that silently aspirate. The difficulty arises in deciding which patients should have an MBS test. Not all patients with a closed head injury or a stroke will aspirate. Further, it is not economically realistic to evaluate all patients with neurologic deficits for aspiration using an MBS test. It would be beneficial therefore to have a method to clinically screen patients with neurologic deficits that have dysphagia, and to more accurately predict which patients are at risk of aspiration and which patients are not.
In accordance with the present invention, the shortcomings of the above-described conventional processes employed by speech pathologists to detect aspiration in patients with neurological deficits are effectively remedied by a cough-based screening process which is operative to clinically detect a (stroke) patient who is at risk for aspiration in both oral and pharyngeal phases of the human swallow. The inventive screening methodology is able to identify those patients who require an MBS test in order to rule out aspiration, and which patients do not need an MBS.
The initial step according to the cough-based screening process of present invention involves a pharyngeal test, in which the patient is given two separate tasks to perform. The patient will have been diagnosed as having had a stroke, and is potentially scheduled to undergo a modified barium swallow (MBS) test. The patient should not be one with a history of asthma or on supplemental oxygen for dyspnea. A speech pathologist performs a preliminary general bedside swallow evaluation and also tests for cognition, voice quality and cranial nerves.
In the first step of the pharyngeal test the patient is required to voluntarily cough. The patient""s ability to voluntarily cough is a reflection of the function of the patient""s efferent motor system, and is graded by the testing pathological specialist as either normal or decreased, if the patient is able to successfully cough. The patient may then optionally be administered a water-holding test, in which the patient is asked to hold a given amount of water in the patient""s mouth for a given period of time.
If the patient is not able to cough voluntarily, the patient is subjected to an inhalation cough test, in which a sensory innervation to the patient""s larynx is tested. As will be described, this sensory innervation test of the patient""s larynx is carried out by stimulating nociceptor (irritant) and C-fibre receptors, using an aerosol chemostimulant that is inhaled through the patient""s mouth.
In accordance with a preferred embodiment of the present invention, the aerosol inhalant, which may be delivered by a standard aerosol inhaler, comprises an atomized solution of tartrate mixed with saline. Although other receptor specific chemostimulants may be employed, studies involving inhaling tartate, reveal that tartrate will stimulate a cough 100% of the time in normal individuals. Further, tartate is considered safe, does not cause pain or discomfort, and has not been shown to cause bronchoconstriction or complications in asthmatics when inhaled in an aerosol form. During the inhalation cough test, the aerosol stimulant is injected into the patient""s mouth by a respiratory therapist, using a nebulizer for a relatively brief period of time. The patient is tested a maximum of three times at different stimulant strengths until a cough is elicited. During each successive stimulant application, the patient receives progressively increasing concentrations of the aerosol for the prescribed period of time by tidal breathing at one minute intervals using successively increasing percentage concentrations.
In response to the patient coughing as a result of the inhaled aerosol stimulant, the inhalation cough test is terminated, regardless of the percentage of concentrations used. The patient""s response to the inhalation test is graded as either a low pneumonia risk (if the patient coughs immediately in response to the initial aerosol spray and the cough appears strong or normal) or a high pneoumonia risk (where the cough appears weak or the patient does not readily cough in response to the initial concentration spray, but requires a more concentrated aerosol application).
Upon completion of the inhalation cough test, the water holding test is conducted. During the water-holding test, the patient is required to take two separate volumes of water into the mouth and hold the water for a specified period of time. Two separate volumes of water are used, since aspiration can occur with large volumes or smaller volumes separately. During the water holding test, the patient is instructed not to swallow any of the water and, at the end of the specified time, to return the held water to a measuring receptacle. Any water that is lost out of the patient""s mouth as a result of a facial droop or poor labial control is collected and measured. Also, the total water returned to the measuring receptacle is calculated, in order to determine if water may have spilled over into the pharynx should there be any of the original volume of water not recollected.